Optical diffusing sheet, optical deflecting sheet, and transmission type screen

ABSTRACT

An optical deflecting sheet for a transmission type screen that emits imaging light projected from an incident side to an emergent side. The optical deflecting sheet includes a highly rigid substrate layer with a light-transmissibility and a high rigidity, and a plurality of layers laminated on the substrate layer. The plurality of layers includes at least a pair of anti-scattering layers disposed on opposite sides of the substrate layer for preventing scattering of the substrate layer. At least one layer of the two or more layers includes an optical deflecting element that deflects imaging light by refracting or reflecting the imaging light. The optical deflecting element is a prism part formed by arranging a plurality of unit prisms each having an incident surface on which light is incident and a total reflecting surface for reflecting at least a part of light incident on the incident surface.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.11/575,613 filed Mar. 20, 2007, now allowed, which in turn is theNational Stage of International Application No. PCT/JP2006/300212 filedJan. 11, 2006, which designated the United States, the entireties ofwhich are incorporated herein by reference.

FIELD OF THE INVENTION

The present invention relates to an optical diffusing sheet and anoptical deflecting sheet for use in a transmission type screen that emitimaging light projected from a light source to an emergent side, and toa transmission type screen that uses at least one of the opticaldiffusing sheet and the optical deflecting sheet.

BACKGROUND OF THE INVENTION

In a rear-projection type display device that projects imaging light ona screen from its rear, a transmission type screen has been used as ascreen for displaying enlarged imaging light projected thereon.Generally, this transmission type screen has been used by combining anoptical deflecting sheet (e.g., Fresnel lens sheet) that collimatesimaging light projected from a light source by deflecting the same inparallel light rays, and emits the light to an observation surface side,and an optical diffusing sheet (e.g., lenticular lens sheet) thatdiffuses imaging light.

The optical deflecting sheet or the optical diffusing sheet used in sucha transmission type screen has been conventionally formed by laminatingan optical element such as a Fresnel lens or a lenticular lens on aplastic substrate made of, e.g., an acryl resin and a polycarbonateresin.

However, since the plastic substrate is sensitive to changes in theenvironment typified by temperature, humidity, and so on, the thicknessand the size of the substrate tend to vary in accordance with changes inthe environment. Thus, there may be a case in which the sheet is warpedso as to generate a float (clearance) between the Fresnel lens sheet andthe lenticular lens sheet. When imaging light is projected on thetransmission type screen under such conditions, there arises a problemof significant decrease in an image quality, such as defocusing, adeterioration in reproducing colors, a double image, and a distortedimage. In particular, when the transmission type screen is used in athin rear-projection television, an angle of incidence of imaging lightincident on the transmission type screen is large. Thus, only a smallwarp or a float generated in the screen considerably deteriorates animage quality of an image projected on the screen. In addition, ascompared with a small-sized screen, a large-sized transmission typescreen involves a problem in that deterioration in an image caused by awarp or a float, which has been generated by changes in the environment,is more conspicuous. At the same time, the large-sized transmission typescreen is more likely to be inflected because of its own weight.

Therefore, a transmission type screen has been developed, that uses aglass substrate which is not easily warped under the influence ofchanges in the environment such as temperature and humidity.

JP2002-357868A discloses a transmission type screen that includes, incombination, a Fresnel lens sheet (described as “Fresnel lens plate” inthe document), and a lenticular lens sheet (described as “lenticularlens plate” in the documents) having a lenticular lens (described as“lenticular lens sheet” in the document) laminated on one surface of aglass substrate. However, this transmission type screen has a problem inthat, since a frontmost surface (surface closest to an observation side)of an emergent side of the transmission type screen is provided by theglass substrate, if the glass substrate is damaged by an accident or thelike, pieces of broken glass are scattered. In this transmission typescreen, mixture of a diffusing agent in the glass substrate isillustrated by way of an example, in order to impart a diffusing effectto the glass substrate. However, there exist the following problems.That is to say, it is not easy to mix a diffusing agent in a glasssubstrate, which increases the manufacturing cost of the glasssubstrate. In addition, mixture of a diffusing agent undesirably makesthe glass substrate fragile, whereby the glass substrate is liable to bebroken.

Besides, JP2001-154274A discloses a structure in which a glass substrateinterposed between a lenticular lens sheet and a Fresnel lens sheet istightly supported by the sheets that have been previously curved inopposite directions by means of a heat treatment. The method disclosedin this Patent Document 2 can be embodied, with use of a Fresnel lenssheet having a Fresnel lens disposed on its incident side. However, whena Fresnel lens sheet having a Fresnel lens disposed on its emergent side(glass-substrate side) is used, this is disadvantageous in that theFresnel lens is rubbed by the glass substrate which tightly contacts asurface on which the Fresnel lens is disposed.

Further, JP2-183241A discloses a transmission type screen that includesa glass substrate with a Fresnel lens directly formed on one surfacethereof, and a plastic sheet with a lenticular lens formed thereon,wherein the plastic sheet is integrally laminated on the other surfaceof the glass substrate. However, there are the following problems. Thatis to say, it is not technically easy to directly form a Fresnel lens ona glass substrate, which leads to increase in the manufacturing cost ofthe glass substrate. Further, it is only one surface of the glasssubstrate that is protected by the plastic sheet, while the oppositesurface of the glass substrate with the Fresnel lens formed thereon isnot protected. Thus, if the glass substrate is broken by an accident orthe like, pieces of the broken glass substrate are scattered, or theFresnel lens is scratched or stained by the pieces. Furthermore, thereis another problem in that, since a concave portion of the Fresnel lensis concentrically subjected to a stress, the Fresnel lens can be easilybroken.

Furthermore, JP2-42401A discloses a screen that includes: a plate-likeFresnel lens sheet having a lens layer attached to a surface of a glasssubstrate via an ultraviolet curing resin, and a protective layer of anultraviolet curing resin layer formed on a surface of the lens layer;and another glass substrate attached on the protective layer. However,in the screen disclosed in this document wherein a frontmost surface isprovided by the glass substrate, there is a problem in that, if theglass substrate is broken, pieces of the broken glass substrate arescattered.

SUMMARY OF THE INVENTION

The object of the present invention is to provide an optical diffusingsheet and an optical deflecting sheet that are capable of preventing adeterioration in an image quality which might be caused by warps of thesheets because of changes in the environment, and are capable of, evenif a substrate is broken by an accident, preventing scattering of piecesof the broken substrate. The another object of the present invention isto provide a transmission type screen including the optical diffusingsheet and/or the optical deflecting sheet.

An optical diffusing sheet according to the present invention is anoptical diffusing sheet for use in a transmission type screen that emitsimaging light projected from an incident side to an emergent side,comprising: a highly rigid substrate layer with a light-transmissibilityand a high rigidity; and two or more layers laminated on the highlyrigid substrate layer, the layers including at least a pair ofanti-scattering layers disposed on opposite sides of the highly rigidsubstrate layer for preventing scattering of the highly rigid substratelayer; wherein at least one layer of the two or more layers includes anoptical diffusing element that diffuses imaging light.

According to the optical diffusing sheet of the present invention, dueto the highly rigid substrate layer with a light-transmissibility and ahigh rigidity, it is possible to restrain a warp of the opticaldiffusing sheet, which might be caused by changes in the environmentsuch as temperature and humidity, and also restrain a flexure of theoptical diffusing sheet, which might be caused by its own weight.Moreover, since the anti-scattering layers are formed on opposite sidesof the highly rigid substrate layer, even when the highly rigidsubstrate layer is broken by an accident such as a collision, scatteringof pieces of the broken substrate can be prevented.

In the optical diffusing sheet according to the present invention, theoptical diffusing element may be a lenticular lens that is formed byarranging a plurality of unit optical shape portions each having arefracting surface that refracts at least a part of imaging lightincident thereon. Alternatively, in the optical diffusing sheetaccording to the present invention, the optical diffusing element may beformed by arranging a plurality of unit optical shape portions eachhaving a total reflecting surface that totally reflects at least a partof imaging light incident thereon.

In the optical diffusing sheet according to the present invention, atleast one layer of the two or more layers may have a first opticaldiffusing element formed by arranging along one direction a plurality ofunit optical shape portions each having a refracting surface forrefracting at least a part of imaging light incident thereon or a totalreflecting surface that totally reflects at least a part of imaginglight incident thereon; and another layer different from the one layerof the two or more layers may have a second optical diffusing elementformed by arranging the plurality of unit optical shape portions alongthe other direction substantially perpendicular to the one direction.According to the optical diffusing sheet, a viewing angle can beenlarged in two directions perpendicular to each other, e.g., a verticaldirection and a lateral direction. Further, according to the opticaldiffusing sheet, a first light absorbing part for absorbing light can bearranged along one direction to correspond to the first opticaldiffusing element, and a second light absorbing part for absorbing lightcan be arranged along the other direction substantially perpendicular tothe one direction to correspond to the second optical diffusing element.With the provision of the first light absorbing part and the secondlight absorbing part, stray light and external light can be effectivelyabsorbed therein, whereby an inconvenience of a double image can bealleviated, and contrast can be enhanced.

An optical deflecting sheet according to the present invention is anoptical deflecting sheet for use in a transmission type screen thatemits imaging light projected from an incident side to an emergent side,comprising: a highly rigid substrate layer with a light-transmissibilityand a high rigidity; and two or more layers laminated on the highlyrigid substrate layer, the layers including at least a pair ofanti-scattering layers disposed on opposite sides of the highly rigidsubstrate layer for preventing scattering of the highly rigid substratelayer; wherein at least one layer of the two or more layers includes anoptical deflecting element that deflects imaging light by refracting orreflecting the imaging light.

According to the optical deflecting sheet of the present invention, dueto the highly rigid substrate layer with a light-transmissibility and ahigh rigidity, it is possible to restrain a warp of the opticaldeflecting sheet, which might be caused by changes in the environmentsuch as temperature and humidity, and also restrain a flexure of theoptical deflecting sheet, which might be caused by its own weight.Moreover, since the anti-scattering layers are formed on opposite sidesof the highly rigid substrate layer, even when the highly rigidsubstrate layer is broken by an accident such as a collision, scatteringof pieces of the broken substrate can be prevented.

In the optical deflecting sheet according to the present invention, theoptical deflecting element may be a Fresnel lens. Alternatively, theoptical deflecting element may be a prism part formed by arranging aplurality of unit prisms each having an incident surface on which lightis incident and a total reflecting surface for reflecting at least apart of light incident on the incident surface.

In the optical deflecting sheet according to the present invention, atleast one layer of the two or more layers may include an opticaldiffusing element that diffuses imaging light incident thereon. In thiscase, the optical diffusing element may be formed by arranging aplurality of unit optical shape portions each having a total reflectingsurface that totally reflects at least a part of imaging light incidentthereon. Such an optical deflecting sheet can provide anintegrally-formed transmission type screen in which troubles such as adouble image can be prevented.

Alternatively, in the optical deflecting sheet according to the presentinvention, at least one layer of the two or more layers may have a firstoptical diffusing element formed by arranging along one direction aplurality of unit optical shape portions each having a refractingsurface that refracts at least a part of imaging light incident thereonor a total reflecting surface that totally reflects at least a part ofimaging light incident thereon; and another layer different from the onelayer of the two or more layers may have a second optical diffusingelement formed by arranging the plurality of unit optical shape portionsalong the other direction substantially perpendicular to the onedirection. Such an optical deflecting sheet can provide anintegrally-formed transmission type screen in which troubles such as adouble image can be prevented. According to the optical deflectingsheet, a viewing angle can be enlarged in two directions perpendicularto each other, e.g., a vertical direction and a lateral direction.Further, according to the optical deflecting sheet, a first lightabsorbing part for absorbing light can be arranged along one directionto correspond to the first optical diffusing element, and a second lightabsorbing part for absorbing light can be arranged along the otherdirection substantially perpendicular to the one direction to correspondto the second optical diffusing element. With the provision of the firstlight absorbing part and the second light absorbing part, stray lightand external light can be effectively absorbed therein, whereby aninconvenience of a double image can be alleviated, and contrast can beenhanced.

Besides, in the optical diffusing sheet or the optical deflecting sheetaccording to the present invention, the highly rigid substrate layer maybe formed of glass or translucent ceramic. This constitution can providean optical diffusing sheet or an optical deflecting sheet with a highdegree of flatness, that is not easily warped by changes in theenvironment such as temperature and humidity.

Further, in the optical diffusing sheet or the optical deflecting sheetaccording to the present invention, at least one layer of the two ormore layers may have a diffusing part that diffuses light. In this case,at least one layer of the two or more layers that is laminated on aposition closer to the incident side than the highly rigid substratelayer, and at least one layer of the two or more layers that islaminated on a position closer to the emergent side than the highlyrigid substrate layer, may have the diffusing parts, respectively. Dueto the provision of the diffusing parts, scintillation (glaring on thescreen) can be reduced, a viewing angle can be enlarged, and uniformityin diffusion can be improved.

Furthermore, in the optical diffusing sheet or the optical deflectingsheet according to the present invention, at least one layer of theanti-scattering layers may have at least one of the following functions:diffusing function, anti-reflection function, anti-glaring function,coloring function, dimmer function, ultraviolet absorption function,antistatic function, soil-resistant function, sensing function, orhard-coating function.

Moreover, in the optical diffusing sheet or the optical deflecting sheetaccording to the present invention, the two or more layers may include ajoining layer that is interposed between the highly rigid substratelayer and the anti-scattering layer so as to join the highly rigidsubstrate layer and the anti-scattering layer to each other. In thiscase, a diffusing agent and an ultraviolet absorbing agent may beincluded in the joining layer. When a diffusing agent is included in thejoining layer, scintillation (glaring on the screen) can be reduced, aviewing angle can be enlarged, and uniformity in diffusion can beimproved. When an ultraviolet absorbing agent is included therein, thescreen can be prevented from turning yellow, which might be caused byultraviolet light.

The present invention is a transmission type screen that includes eitherone or both of any of the above-described optical diffusing sheets andone of any of the above-described optical deflecting sheets.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a first embodiment of a transmissiontype screen according to the present invention;

FIG. 2 is a sectional view of a rear projection television using thefirst embodiment of the transmission type screen;

FIG. 3 is a schematic view of a layer structure of the first embodimentof the transmission type screen;

FIG. 4 is a schematic view of a layer structure of a modification of aFresnel lens sheet of the first embodiment of the transmission typescreen;

FIG. 5 is a schematic view of a layer structure of a modification of theFresnel lens sheet of the first embodiment of the transmission typescreen;

FIG. 6 is a schematic view of a layer structure of a modification of alenticular lens sheet of the first embodiment of the transmission typescreen;

FIG. 7 is a schematic view of a layer structure of a modification of thelenticular lens sheet of the first embodiment of the transmission typescreen;

FIG. 8 is a schematic view of a layer structure of a modification of thelenticular lens sheet of the first embodiment of the transmission typescreen;

FIG. 9 is a schematic view of a layer structure of a modification of thelenticular lens sheet of the first embodiment of the transmission typescreen;

FIG. 10 is a schematic view of a layer structure of a modification ofthe lenticular lens sheet of the first embodiment of the transmissiontype screen;

FIG. 11 is a perspective view of a second embodiment of the transmissiontype screen according to the present invention;

FIG. 12 is a schematic view of a layer structure of the secondembodiment of the transmission type screen;

FIG. 13 is a partial sectional view of an optical diffusing element;

FIG. 14 is a schematic view of a layer structure of a modification of anoptical diffusing sheet of the second embodiment of the transmissiontype screen;

FIG. 15 is a perspective view of a third embodiment of the transmissiontype screen according to the present invention;

FIG. 16 is a sectional view of a rear projection television using thethird embodiment of the transmission type screen;

FIG. 17 is a schematic view of a layer structure of the third embodimentof the transmission type screen;

FIG. 18 is a partial sectional view of a prism part;

FIG. 19 is a schematic view of a layer structure of a modification of aprism sheet of the third embodiment of the transmission type screen;

FIG. 20 is a perspective view of a fourth embodiment of the transmissiontype screen according to the present invention;

FIG. 21 is a schematic view of a layer structure of the fourthembodiment of the transmission type screen;

FIG. 22 is a perspective view of a fifth embodiment of the transmissiontype screen according to the present invention;

FIG. 23 is a schematic view of a layer structure of the fifth embodimentof the transmission type screen;

FIG. 24 is a schematic view of a layer structure of a modification ofthe first embodiment of the transmission type screen;

FIG. 25 is a schematic view of a layer structure of a modification ofthe fifth embodiment of the transmission type screen;

FIG. 26 is a perspective view of assistance in explaining a layerstructure of a modification of the transmission type screen according tothe present invention;

FIG. 27 is a schematic view of a layer structure of a modification ofthe transmission type screen according to the present invention;

FIG. 28 is a schematic view of a layer structure of a modification ofthe transmission type screen according to the present invention;

FIG. 29 is a schematic view of a layer structure of a modification ofthe transmission type screen according to the present invention;

FIG. 30 is a schematic view of a layer structure of a modification ofthe transmission type screen according to the present invention;

FIG. 31 is a schematic view of a layer structure of a modification ofthe transmission type screen according to the present invention; and

FIG. 32 is a schematic view of a layer structure of a modification ofthe transmission type screen according to the present invention.

DETAILED DESCRIPTION OF THE INVENTION

Embodiments of an optical diffusing sheet, an optical deflecting sheet,and a transmission type screen will be described hereinafter, withreference to the drawings.

In the following embodiments, the transmission type screen includeseither one of the optical diffusing sheet and the optical deflectingsheet, or both the optical diffusing sheet and the optical deflectingsheet. A rear-projection type display device is formed by using the thusobtained transmission type screen. The optical diffusing sheetcomprises: a highly rigid substrate layer with a light-transmissibilityand a high rigidity; and two or more layers laminated on the highlyrigid substrate layer, the layers including at least a pair ofanti-scattering layers disposed on opposite sides of the highly rigidsubstrate layer for preventing scattering of the highly rigid substratelayer; wherein at least one layer of the two or more layers includes anoptical diffusing element that diffuses imaging light. Such an opticaldiffusing sheet is a sheet-like member for diffusing imaging lightincident thereon. The optical deflecting sheet is for use in atransmission type screen that emits imaging light projected from anincident side to an emergent side, and comprises: a highly rigidsubstrate layer with a light-transmissibility and a high rigidity; andtwo or more layers laminated on the highly rigid substrate layer, thelayers including at least a pair of anti-scattering layers disposed onopposite sides of the highly rigid substrate layer for preventingscattering of the highly rigid substrate layer; wherein at least onelayer of the two or more layers includes an optical deflecting elementthat deflects imaging light by refracting or reflecting the imaginglight. Such an optical deflecting sheet is a sheet-like member foremitting imaging light incident thereon by deflecting the imaging lightin a direction substantially perpendicular to the optical deflectingsheet.

The optical diffusing sheet, the optical deflecting sheet, and thetransmission type screen are described below, based on some concreteembodiments. However, it should be noted that the present invention isnot limited to the following embodiments.

First Embodiment

FIG. 1 is a view of a first embodiment of a transmission type screenaccording to the present invention. FIG. 2 is a sectional view of a rearprojection television using the first embodiment of the transmissiontype screen.

As shown in FIG. 1, the transmission type screen 100 in the firstembodiment includes an optical deflecting sheet disposed on an incidentside (light source side) of imaging light L, and an optical diffusingsheet disposed on an emergent side (observation surface side) of theimaging light L. The transmission type screen 100 is positioned on animage-formation surface of the imaging light L. In this transmissiontype screen, the optical diffusing sheet is formed as a lenticular lenssheet having a lenticular lens, while the optical deflecting sheet isformed as a Fresnel lens sheet having a Fresnel lens.

As shown in FIG. 2, the rear projection television 1 is an image displaydevice of rear-projection type that includes: the transmission typescreen 100, a light source part 21 disposed on an opposite side(hereinafter also referred to as “incident side”) of the transmissiontype screen 100 relative to the observation surface side; and a mirrorpart 31 for reflecting the imaging light L projected from the lightsource part 21. In this embodiment, the light source part 21 is of asingle tube type using a DMD.

FIG. 3 is a schematic view of a layer structure of the first embodimentof the transmission type screen. A traveling direction of the imaginglight L is designated by an arrow in FIG. 3, and in the viewsschematically showing a layer structure of the transmission type screen,which are referred to hereinbelow. In the respective views, a layer inwhich circles are distributed denotes a layer that contains a diffusingagent for diffusing light without directivity.

Fresnel Lens Sheet (Optical Deflecting Sheet)

The Fresnel lens sheet 110 is described at first. As shown in FIG. 3,the Fresnel lens sheet 110 includes a first glass substrate 111, a firstanti-scattering layer 112, a third anti-scattering layer 113, andjoining layers 114-1 and 114-2. The Fresnel lens sheet 110 is disposedon the incident side of the transmission type screen 100.

The first glass substrate (highly rigid substrate layer) 111 in thisembodiment is a glass plate formed of silicate glass. The first glasssubstrate 111 has a high light-transmissibility and a high rigidity. Athickness of the glass plate used in the first glass substrate 111 ispreferably in a range between 1.5 mm to 3 mm. In this embodiment, theglass plate is 2 mm in thickness. It is preferable that a transmittanceof the first glass substrate 111 relative to light whose wavelength bandis between 400 nm and 700 nm be equal to or more than 90%.

The joining layer 114-1 is a layer for integrally joining the firstglass substrate 111 and the below-described first anti-scattering layer112, while the joining layer 114-2 is a layer for integrally joining thefirst glass substrate 111 and the below-described third anti-scatteringlayer 113. The joining layers 114-1 and 114-2 are formed of anultraviolet-curing type acryl resin which is cured by an ultravioletirradiation. A thickness of each of the joining layers 114-1 and 114-2may be 100 μm, for example. The joining layer 114-1 is interposedbetween the first glass substrate 111 and the first anti-scatteringlayer 112. The joining layer 114-2 is interposed between the first glasssubstrate 111 and the third anti-scattering layer.

The first anti-scattering layer 112 is integrally laminated on theincident side of the first glass substrate 111 through the joining layer114-1. If the first glass substrate 111 is, for example, broken anddamaged, the first anti-scattering layer 112 exhibits a function forpreventing scattering of pieces of the damaged first glass substrate111. In this embodiment, the first anti-scattering layer 112 is anall-purpose anti-reflection sheet having a function of preventingreflection, that is formed of an acryl resin or the like, with athickness of 80 μm.

The third anti-scattering layer 113 is integrally laminated on theemergent side of the first glass substrate 111 through the joining layer114-2. If the first glass substrate 111 is, for example, broken anddamaged, the third anti-scattering layer 113 exhibits a function forpreventing scattering of pieces of the damaged first glass substrate111. The third anti-scattering layer 113 includes an optical deflectingelement base material part (Fresnel base material part) 113 b, and anoptical deflecting element (Fresnel lens part) 113 a that is formed onone surface of the Fresnel base material part 113 b by using anultraviolet curing resin. The third anti-scattering layer 113 as alayered body composed of the Fresnel base material part 113 b and theFresnel lens part 113 a is further laminated on the first glasssubstrate 111.

The Fresnel base material part 113 b is a member that serves as a basefor the third anti-scattering layer 113. A thickness of the Fresnel basematerial part 113 b may be, e.g., 200 μm. The Fresnel base material part113 b may be formed of an acryl resin, in which glass beads are mixed asa diffusing agent, so as to function as a diffusing part for diffusinglight. It is preferable to use glass beads each having a diameter equalto or more than 1 μm, in order that the diffusion does not depend on awavelength of light. Herein, the “diffusing part” means a part having adiffusing function without directivity, that is, for example, formed by:dispersing particles formed of organic or inorganic compounds in amember serving as a base material; coating a surface of the member withparticles formed of organic or inorganic compounds; or providing fineirregular-shaped portions on the surface of the member.

The Fresnel lens part (optical deflecting element) 113 a is integrallyformed on the emergent side of the Fresnel base material part 113 b. TheFresnel lens part 113 a functions as a Fresnel lens that refracts theimaging light L incident thereon from the incident side in apredetermined direction, and emits the imaging light L to the emergentside as parallel light rays. The Fresnel lens part 113 a may be formedby means of a die for molding a Fresnel lens, not shown, having aninverted shape of the Fresnel lens. Specifically, a molding die isheated at first, and a surface of the molding die is coated with anultraviolet curing resin. Then, the Fresnel base material part 113 b iscompressively laminated on the ultraviolet curing resin filled in thedie, with maintaining a temperature of the coated ultraviolet curingresin. Thereafter, the ultraviolet curing resin is irradiated with anultraviolet light so as to be cured, and the cured resin is peeled fromthe die. In this manner, the Fresnel lens part 113 a can be integrallyformed on the Fresnel base material part 113 b. The ultraviolet curingresin is preferably urethane acrylate, epoxy acrylate, and so on, but isnot specifically limited thereto.

Lenticular Lens Sheet (Optical Diffusing Sheet)

Next, the lenticular lens sheet 120 is described. As shown in FIG. 3,the lenticular lens sheet 120 includes a second glass substrate 121, asecond anti-scattering layer 123, a fourth anti-scattering layer 122,and joining layers 124-1 and 124-2. The lenticular lens sheet 120 is anoptical diffusing sheet that diffuses the imaging light L by refractingthe same, and is disposed on the emergent side of the transmission typescreen 100.

Similar to the first glass substrate 111, the second glass substrate(highly rigid substrate layer) 121 is a glass plate formed of silicateglass, with a thickness of, e.g., 2 mm. The second glass substrate(highly rigid substrate layer) 121 has a high light-transmissibility anda high rigidity, and preferably has a transmittance of equal to or morethan 90% relative to light whose wavelength band is between 400 nm and700 nm, similar to the first glass substrate 111. The joining layer124-1 is a layer for integrally joining the second glass substrate 121and the fourth anti-scattering layer 122, while the joining layer 124-2is a layer for integrally joining the second glass substrate 121 and thesecond anti-scattering layer 123. Each of the joining layers 124-1 and124-2 is a layer which is formed of, e.g., an ultraviolet-curing typeacryl resin, and has a thickness of 100 μm.

The fourth anti-scattering layer 122 is integrally laminated on theincident side of the second glass substrate 121 through the joininglayer 124-1. If the second glass substrate 121 is damaged, the fourthanti-scattering layer 122 exhibits a function for preventing scatteringof pieces of the damaged second glass substrate 121. The fourthanti-scattering layer 122 includes: an optical diffusing element basematerial part (lenticular base material part) 122 b; an opticaldiffusing element (lenticular lens part) 122 a formed on one surface ofthe lenticular base material part 122 b by using a thermoplastic resin;and light absorbing parts 122 c for absorbing light that are formed onthe lenticular base material part 122 b on a surface thereof which doesnot face the lenticular lens part 122 a. In this case, the fourthanti-scattering layer 122 may be formed by extrusion molding. In thisembodiment, the lenticular lens part 122 a is formed by using athermoplastic resin by way of example. However, not limited thereto, thelenticular lens part 122 a may be formed by curing an ultraviolet curingresin or the like on the optical diffusing element base material part(lenticular base material part) 122 b formed of a polyethyleneterephthalate resin, similar to the Fresnel lens part 113 a. The fourthanti-scattering layer 122 as a layered body composed of the lenticularbase material part 122 b and the lenticular lens part 122 a is furtherlaminated on the second glass substrate 121.

The lenticular base material part 122 b is a sheet-like member with athickness of, e.g., 200 μm, that serves as a base for the fourthanti-scattering layer 122. The lenticular base material part 122 b maybe formed of an acryl resin in which glass beads are mixed as adiffusing agent, to function as a diffusing part.

The lenticular lens part 122 a is an optical diffusing element that isintegrally formed on an incident-side surface of the lenticular basematerial part 122 b. The optical diffusing element is an optical elementincluding a lens shape or prism shape having a light diffusing effect,and is constituted by arranging a plurality of unit optical shapeportions that refract or reflect light. The lenticular lens part 122 ais formed by arranging, along one direction substantially perpendicularto a line normal to the lenticular base material part 122 b, forexample, along a horizontal direction or vertical direction, a pluralityof unit lenses (unit optical shape portions) having a function ofdiffusing imaging light. The unit lenses have almost semielliptic-shapedcross-sections, and protrude toward the incident side. The unit lensesare unit optical shape portions each having a refracting surface thatrefracts at least a part of imaging light incident thereon. The lightabsorbing parts 122 c are arranged so as to form a stripe pattern on anemergent-side surface of the lenticular base material part 122 b atareas through which the imaging light does not pass. Thus, the arrangingdirection of the light absorbing parts 122 c and that of the unit lenses(unit optical shape portions) conform to each other.

The second anti-scattering layer 123 is integrally joined to theemergent side of the second glass substrate 121 through the joininglayer 124-2. If the second glass substrate 121 is, for example, brokenand damaged, the second anti-scattering layer 123 exhibits a functionfor preventing scattering of pieces of the damaged second glasssubstrate 121. The second anti-scattering layer 123 may be formed bysubstantially uniformly mixing glass beads as a diffusing agent in apolyethylene terephthalate resin or the like, and may be a sheet-likemember which is 188 μm in thickness, for example. In this case, thesecond anti-scattering layer 123 functions as a light diffusing part fordiffusing light without directivity.

The transmission type screen 100 composed of, in combination, thelenticular lens sheet 120 and the Fresnel lens sheet 110 in thisembodiment provides the following effects. The Fresnel lens sheet 110and the lenticular lens sheet 120 respectively include the first glasssubstrate 111 and the second glass substrate 121 as substrates. Thus, itis possible to restrain the generation of a warp and a float of theFresnel lens sheet 110 or the lenticular lens sheet 120, which might becaused by changes in the environment such as temperature and humidity.It is also possible to restrain the generation of a flexure of theFresnel lens sheet 110 or the lenticular lens sheet 120, which might becaused by their own weights. As a result, distortion of an image can beprevented, while a high degree of flatness of the sheets can improve animage quality.

In the Fresnel lens sheet 110, the first and third anti-scatteringlayers 112 and 113 are integrally laminated on the opposite surfaces ofthe first glass substrate 111. In the lenticular lens sheet 120, thesecond and fourth anti-scattering layers 123 and 122 are disposed on theopposite surfaces of the second glass substrate 121. Thus, if the firstor second glass substrate 111 or 121 is damaged by an accident or thelike, during an operation where the Fresnel lens sheet 110 or thelenticular lens sheet 120 is independently handled, scattering of piecesof the damaged substrate can be prevented.

In the transmission type screen 100 using the Fresnel lens sheet 110 andthe lenticular lens sheet 120, a surface closest to the incident sideand a surface closest to the emergent side of the transmission typescreen 100 are respectively covered with the anti-scattering layers.Thus, if the first and the second glass substrates 111 and 121 in thetransmission type screen 100 are cracked or broken by an accident suchas a collision, scattering of pieces of the cracked or broken substratescan be prevented.

Since the first anti-scattering layer 112 is an anti-reflection sheethaving a function of preventing reflection, when the imaging light Lenters the transmission type screen 100, the first anti-scattering layer112 reduces stray light which is generated by the reflection of theimaging light L on a surface closest to the incident side (surfaceclosest to the light source) of the transmission type screen 100. Thus,the generation of a double image (ghost), which is caused when the straylight is reflected again by the mirror part 31 so as to re-enter thetransmission type screen 100, can be reduced so as to thereby enhance animage quality.

The lenticular base material member 122 b and the second anti-scatteringlayer 123 include therein substantially uniformly mixed glass beads as adiffusing agent so as to function as diffusing parts. Thus, a viewingangle can be enlarged, while a uniformity of diffusion can be improved.In addition, it is possible to reduce scintillation (glaring on thescreen) which tends to be generated because of the use of the lightsource part of a single tube type such as a DMD. Therefore, an image ofa high quality can be provided to an observer.

The Fresnel base material member 113 b and the lenticular base materialpart 122 b include therein substantially uniformly mixed glass beads asa diffusing agent so as to function as diffusing parts. Thus, it is notrequired to additionally dispose a diffusing layer having a diffusingeffect, which can result in the reduced number of layers in the entiretransmission type screen 100. As a result, a thickness and a weight ofthe transmission type screen 100 can be reduced, and the manufacturingprocess of the transmission type screen 100 can be simplified.

Modifications of First Embodiment

(1) FIGS. 4 and 5 are schematic views of layer structures ofmodifications of the Fresnel lens sheet (the optical deflective sheet)in the first embodiment. In FIGS. 4 and 5, and other schematic views ofa layer structure of the transmission type screen, which are referred tohereinbelow, a layer whose boundary face (interface) portion isrepresented by a corrugated line denotes a layer having fineirregular-shaped portions on its surface.

In this embodiment, the Fresnel lens sheet 110 functions as a diffusingpart, since glass beads as a diffusing agent are substantially uniformlymixed in the Fresnel base material part 113 b. However, a position ofthe layer functioning as a diffusing part where light is diffusedwithout directivity, and the number thereof are not specifically limitedto this example. Although modifications of the diffusing part is shownbelow, a constitution of the diffusing part is not limited to thefollowing modifications.

As shown in FIG. 4( a), in addition to mixing a diffusing agent in aFresnel base material part 113 b-2 in a Fresnel lens sheet 110, adiffusing agent may be mixed in a joining layer 114-1-2 interposedbetween a first glass substrate 111 and a first anti-scattering layer112, so that the joining layer 114-1-2 can function as a diffusing part.Alternatively, as shown in FIG. 4( b), a diffusing agent may be mixed ina joining layer 114-2-2 interposed between a first glass substrate 111and a third anti-scattering layer 113, so that the joining layer 114-2-2can function as a diffusing part. Alternatively, as shown in FIG. 4( c),instead of mixing a diffusing agent, an incident-side surface of aFresnel base material part 113 b-3 may have fine irregular-shapedportions, so that the Fresnel base material part 113 b-3 can function asa diffusing part. In this modification, a difference between arefractive index of the Fresnel base material part 113 b-3 and that of ajoining layer 114-2 is preferably large, in order to obtain a moreadvantageous diffusion effect. Not limited to this example, when fineirregular-shaped portions are formed on a surface of a layer so as toimpart thereto a function as a diffusing part, it is preferable that adifference between refractive indexes of two layers, between which theirregular interface is formed, be as large as possible, in terms ofachieving a significantly high diffusing effect.

Alternatively, as shown in FIG. 5( d), instead of mixing a diffusingagent in a Fresnel base material part 113 b-2 in a Fresnel lens sheet110, a lenticular lens part 112 a-2 having an effect of diffusing lightin a vertical direction and a lenticular base material part 112 b-2 maybe disposed on a first anti-scattering layer 112-2, so that the firstanti-scattering layer 112-2 can function as a diffusing part. Althoughnot shown, the first anti-scattering layer 112-2 may have, instead ofthe lenticular lens part 112 a-2, an optical diffusing element formed byarranging a plurality of unit prism shape portions each having asubstantially triangular-shaped cross-section and protruding toward theincident side.

Alternatively, as shown in FIG. 5( e), instead of mixing a diffusingagent in a Fresnel base material part 113 b-2 in a Fresnel lens sheet110, a first anti-scattering layer 112-3 may be formed of a 188 μm thicklayer which is formed by substantially uniformly mixing glass beads(diffusing agent) in a polyethylene terephthalate resin, so that thefirst anti-scattering layer 112-3 can function as a diffusing part.Although not shown, fine irregular-shaped portions may be formed on anincident-side surface of the first anti-scattering layer, so that thefirst anti-scattering layer can function as a diffusing part.

(2) FIGS. 6 to 10 are schematic views of layer structures ofmodifications of the lenticular lens sheet (the optical diffusing sheet)in the first embodiment.

In this embodiment, the lenticular lens sheet 120 functions as adiffusing part, since glass beads as a diffusing agent are substantiallyuniformly mixed in the lenticular base material part 122 b. The secondanti-scattering layer 123 functions as a diffusing part, since glassbeads as a diffusing agent are substantially uniformly mixed therein.However, a position of the layer functioning as a diffusing part wherelight is diffused without directivity, and the number thereof are notspecifically limited to this example. Although modifications of thediffusing part are shown below, a constitution of the diffusing part isnot limited to the following modifications.

As shown in FIGS. 6( a) to 6(c), layers functioning as diffusing partsmay be disposed on the incident side and the emergent side of a secondglass substrate 121, without mixing a diffusing agent in a lenticularbase material part 122 b-2 in a lenticular lens sheet 120. In theexample shown in FIG. 6( a), between a second glass substrate 121 and afourth anti-scattering layer 122, there is laminated a 188 μm thickdiffusing layer 125-1 which is formed by substantially uniformly mixinga diffusing agent such as glass beads in a polyethylene terephthalateresin. The diffusing layer 125-1 is laminated through joining layers124-3 and 124-4. In the modification shown in FIG. 6( b), a diffusinglayer 125-1 is laminated through joining layers 124-3 and 124-4, similarto the example shown in FIG. 6( a). Instead of mixing a diffusing agentin a second anti-scattering layer 123-2, a diffusing agent is mixed in ajoining layer 124-2-2 interposed between a second glass substrate 121and a second anti-scattering layer 123-2, so that the joining layer124-2-2 can function as a diffusing part. Alternatively, in themodification shown in FIG. 6( c), instead of mixing a diffusing agent ina second anti-scattering layer 123-3, fine irregular-shaped portions areformed on a surface of the second anti-scattering layer 123-3, so thatthe second anti-scattering layer 123-3 can function as a diffusing part.

Alternatively, as shown in FIG. 7( d), instead of mixing a diffusingagent in a second anti-scattering layer 123-2 in a lenticular lens sheet(the optical diffusing sheet) 120, a diffusing layer 125-2 similar tothe diffusing layer 125-1 may be laminated between a second glasssubstrate 121 and the second anti-scattering layer 123-2 through joininglayers 124-5 and 124-6. Alternatively, in the example shown in FIG. 7(e), instead of mixing a diffusing agent in a lenticular base materialpart 122 b-2, a diffusing agent is substantially uniformly mixed in ajoining layer 124-1-2 interposed between a second glass substrate 121and a fourth anti-scattering layer 122, so that the joining layer124-1-2 can function as a diffusing part. On the other hand, in theexample shown in FIG. 7( f), instead of mixing a diffusing agent in alenticular base material part 122 b-3, fine irregular-shaped portionsare formed on a surface of the lenticular base material part 122 b-3, sothat a fourth anti-scattering layer 122 (lenticular base material part122 b-3) can have a diffusing part.

FIGS. 8 and 9 show examples in which a diffusing part is not disposed asan additional layer. In the example shown in FIG. 8( g), instead ofmixing a diffusing agent in a second anti-scattering layer 123-3, fineirregular-shaped portions are formed on a surface of the secondanti-scattering layer 123-3, so that the second anti-scattering layer123-3 can have a diffusing part. Alternatively, as shown in FIG. 8( h),instead of mixing a diffusing agent in a second anti-scattering layer123-2, a diffusing agent may be substantially uniformly mixed in ajoining layer 124-2-2 interposed between a second glass substrate 121and a second anti-scattering layer 123-2, so that the joining layer124-2-2 can have a diffusing part. Moreover, although not shown, insteadof mixing a diffusing agent in a lenticular base material part 122 b,fine irregular-shaped portions may be formed on a surface of thelenticular base material part 122 b, so that the lenticular basematerial part 122 b can have a diffusing part.

Alternatively, as shown in FIG. 9( i), instead of mixing a diffusingagent in a lenticular base material part 122 b-2, a diffusing agent maybe mixed in a joining layer 124-1-2, so that the joining layer 124-1-2can have a diffusing part. Alternatively, as shown in FIG. 9( j),instead of mixing a diffusing agent in a second anti-scattering layer123-3, fine irregular-shaped portions may be formed on a surface of thesecond anti-scattering layer 123-3. In the example shown in FIG. 9( j),a joining layer 124-1-2 and the second anti-scattering layer 123-3respectively have diffusing parts. Alternatively, as shown in FIG. 9(k), instead of mixing a diffusing agent in a lenticular base materialpart 122 b-2 and a second anti-scattering layer 123-2, a diffusing agentmay be mixed in a joining layer 124-1-2 which integrally laminates asecond glass substrate 121 on a fourth anti-scattering layer 122, and adiffusing agent may be mixed in a joining layer 124-2-2 which integrallylaminates the second glass substrate 121 on a second anti-scatteringlayer 123-2, so that the two joining layers 124-1-2 and 124-2-2 canrespectively have diffusing parts.

In addition, two diffusing parts may be disposed on positions closer tothe incident side than the second glass substrate 121. In the exampleshown in FIG. 10( l), instead of mixing a diffusing agent in a secondanti-scattering layer 123-2, a diffusing layer 125-2 is interposedbetween a second glass substrate 121 and a fourth anti-scattering layer122. In this example, instead of mixing a diffusing agent in alenticular base material part 122 b, fine irregular-shaped portions maybe formed on a surface of the lenticular base material part 122 b,although not shown, so that the lenticular base material part 122 b canhave a diffusing part.

As in the above modifications in which a function as a diffusing parthaving a diffusing effect is imparted to two layers which are notadjacent to each other and are disposed on positions closer to theemergent side than the Fresnel lens part 113 a in the transmission typescreen 100, a viewing angle can be enlarged, uniformity in diffusion canbe enhanced, and scintillation can be reduced. As a result, an imagequality can be remarkably improved.

(3) In this embodiment, an example in which the optical diffusingelement 122 a is formed of a lenticular lens is shown. However, notlimited thereto, the optical diffusing element may be formed of amicrolens array or the like.

(4) In this embodiment, the fourth anti-scattering layer 122 includesthe optical diffusing element, more specifically, the lenticular lenspart 122 a and the lenticular base material part 122 b, which is shownby way of example. Not limited thereto, as show in FIG. 10( m), forexample, a second anti-scattering layer 123-4 may include a lenticularlens part 123 a-4 and a lenticular base material part 123 b-4. In theexample shown in FIG. 10( m), although a diffusing agent issubstantially uniformly mixed in the lenticular base material part 123b-4 and a fourth anti-scattering layer 122-2, a position of the layerfunctioning as a diffusing part where light is diffused withoutdirectivity and the number thereof are not specifically limited, asdescribed in the above modifications.

Second Embodiment

FIG. 11 is a second embodiment of the transmission type screen accordingto the present invention. As shown in FIG. 11, the transmission typescreen 400 in the second embodiment includes an optical deflecting sheetdisposed on an incident side of imaging light L, and an opticaldiffusing sheet 420 disposed on an emergent side of the imaging light L.The transmission type screen 400 in the second embodiment is used in therear projection television 1 shown in FIG. 2, similar to thetransmission type screen 100 described in the first embodiment.

The optical deflecting sheet 410 in this transmission type screen isformed as a Fresnel lens sheet having a Fresnel lens, similar to thefirst embodiment. Meanwhile, the optical diffusing sheet 420 is formedof a sheet-like member which is different from that of the firstembodiment, as described below.

FIG. 12 is a schematic view of a layer structure of the secondembodiment of the transmission type screen.

The Fresnel lens sheet (the optical deflective sheet) 410 is identicalto the Fresnel lens sheet 110 shown in the first embodiment, andincludes a first glass substrate 411, a first anti-scattering layer 412,a third anti-scattering layer 413, and joining layers 414-1 and 414-2.The first glass substrate 411, the first anti-scattering layer 412, thethird anti-scattering layer 413, and the joining layers 414-1 and 414-2in the Fresnel lens sheet 410 in this embodiment respectively correspondto the first glass substrate 111, the first anti-scattering layer 112,the third anti-scattering layer 113, and the joining layers 114-1 and114-2 in the Fresnel lens sheet 110 in the first embodiment, and thushave the same functions corresponding thereto. Therefore, theoverlapping description for the Fresnel lens sheet (the opticaldeflecting sheet) 410 in the second embodiment is omitted.

Optical Diffusing Sheet

The optical diffusing sheet 420 is disposed on the emergent side of thetransmission type screen 400, and includes a second glass substrate 421,a second anti-scattering layer 423, a fourth anti-scattering layer 422,and joining layers 424-1 and 424-2. The optical diffusing sheet 420 isan optical sheet that diffuses imaging light incident thereon by totallyreflecting at least a part of the imaging light. The second glasssubstrate 421 is a highly rigid substrate layer that has a highlight-transmissibility and a high rigidity. The second glass substrate421 in this embodiment is a glass plate formed of silicate glass, andhas a thickness of 3 mm. In this embodiment, a transmittance of thesecond glass substrate 421 relative to light whose wavelength band isbetween 400 nm and 700 nm is equal to or more than 90%.

The joining layer 424-1 is a layer for integrally joining the secondglass substrate 421 and the fourth anti-scattering layer 422 which isdescribed below, while the joining layer 424-2 is a layer for joiningthe second glass substrate 421 and the second anti-scattering layer 423which is described below. Each of the joining layer 424-1 and 424-2 maybe formed of an acryl resin of pressure sensitive adhesion type whichmanifests an adhesion property when a pressure is applied thereto, andmay be 20 μm in thickness. Not limited 20 μm, the thicknesses of thejoining layers 424-1 and 424-2 can be suitably changed, but preferablyfall within a range of from 20 μm to 30 μm.

The fourth anti-scattering layer 422 is a member that is integrallylaminated on the incident side of the second glass substrate 421 throughthe joining layer 424-1. If the second glass substrate 421 is broken,for example, the fourth anti-scattering layer 422 exhibits a functionfor preventing scattering of pieces of the broken second glass substrate421. The fourth anti-scattering layer 422 includes an optical diffusingelement base material part 422 b, and an optical diffusing element 422 aformed on one surface of the optical diffusing element base materialpart 422 b. Similar to the Fresnel lens part 113 a shown in the firstembodiment, the optical diffusing element 422 a may be formed by usingan ultraviolet curing resin. The fourth anti-scattering layer as alayered body composed of the optical diffusing element 422 a and theoptical diffusing element base material part 422 b is further laminatedon the second glass substrate 421.

The optical diffusing element base material part 422 b is a sheet-likemember with a thickness of e.g., 200 μm that serves as a base for thefourth anti-scattering layer 422. The optical diffusing element basematerial part 422 b may be formed of an acryl resin, in which diffusingagent such as glass beads is mixed, so as to function as a diffusingpart.

FIG. 13 is a partial sectional view of the optical diffusing element.The optical diffusing element 422 a has, on the emergent side thereof, aplurality of unit optical shape portions 422 c that are arranged so asto protrude toward the side of an observer. Similar to the Fresnel lenspart 113 a shown in the first embodiment, the unit optical shapeportions 422 c may be formed by using an ultraviolet curing resin. Asshown in FIG. 13, the unit optical shape portion 422 c has asubstantially trapezoidal-shaped cross-section, and protrudes toward theemergent side. A clearance having a substantially triangular-shapedcross-section is formed between two unit optical shape portions 422 cadjacent to each other. A light absorbing part 422 d for absorbing lightthat has a shape corresponding to that of the clearance is disposed inthe clearance so as to fill the same. As compared with the unit opticalshape portions 422 c, the light absorbing parts 422 d are formed of amaterial having a lower refractive index. The optical diffusing element422 a totally reflects at least a part of light incident thereon fromlower base of the unit optical shape portions 422 c in predetermineddirections, by slant portions 422 e of the unit optical shape portions422 c. The totally reflected light is diffused and goes out of upperbase of the unit optical shape portions 422 c. In this manner, theoptical diffusing element 422 a can exert a diffusing effect.

As shown in FIG. 12, unit prism shape portions 440, that havesubstantially triangular-shaped cross-sections and protrude toward theincident side, are formed on an incident-side surface of the opticaldiffusing element base material part 422 b in the optical diffusingsheet 420 in this embodiment. The unit prism shape portions 440 have thesubstantially triangular-shaped cross-sections which are smaller thanthose of the light absorbing parts 422 d, and are arranged at smallerpitches than those of the light absorbing parts 422 d. Similar to thelight absorbing parts 422 d, the unit prism shape portions 440 areextended along the light absorbing part 422 d in an elongatedarrangement. With a provision of these prism shape portions orirregular-shaped portions, outside light incident from the observationsurface side (emergent side) of the transmission type screen 400 can bereflected in the vertical or horizontal direction. Thus, outside lightcan be efficiently absorbed in the light absorbing parts 422 d, so thatthe deterioration in image quality such as deterioration in contrast,which might be caused by outside light, can be decreased. Instead of theunit prism portions 440 each having a substantially triangular-shapedcross-section, irregular-shaped portions, which are disposed on theincident-side surface of the optical diffusing element base materialpart 422 b, can provide an effect substantially the same as that of theunit prism shape portions 440.

As shown in FIG. 12, the second anti-scattering layer 423 is integrallylaminated on the emergent side of the second glass substrate 421 throughthe joining layer 424-2. If the second glass substrate 421 is, forexample, broken and damaged, the second anti-scattering layer 423exhibits a function for preventing scattering of pieces of the damagedsecond glass substrate 421. The second anti-scattering layer 423 may beformed by substantially uniformly mixing glass beads as a diffusingagent in a polyethylene terephthalate resin or the like so as tofunction as a diffusing part. A thickness of the second anti-scatteringlayer 423 may be, e.g., 188 μm.

According to the transmission type screen 400 in the second embodimentincluding the optical diffusing sheet 420 and the Fresnel lens sheet(the optical deflecting sheet) 410, effects substantially the same asthose of the transmission, type screen 100 shown in the first embodimentcan be obtained. That is to say, according to the transmission typescreen 400 in the second embodiment, it is possible to restrain thegeneration of a warp and a float of the optical diffusing sheet 420 orthe Fresnel lens sheet 410, which might be caused by changes in theenvironment such as temperature and humidity. It is also possible torestrain the generation of a flexure of the optical diffusing sheet 420or the Fresnel lens sheet 410, which might be caused by their ownweights. Thus, the transmission type screen can have a high degree offlatness, so that an image of high quality can be provided. Similar tothe transmission type screen 100 shown in the first embodiment,according to the transmission type screen 400 in the second embodiment,if the first and second glass substrates 411 and 421 are, for example,broken and damaged, scattering of pieces of the damaged substrates canbe prevented.

The transmission type screen 400 in the second embodiment can furtherprovide the following effects. The optical diffusing element 422 a usedin the optical diffusing sheet 420 can be easily manufactured at a highprecision. Thus, the optical diffusing sheet, the optical deflectingsheet, and the transmission type screen that provide an image of highquality can be obtained at lower costs.

The optical diffusing sheet 420 in the second embodiment enables a finepitch. Thus, as compared with the transmission type screen 100 using thelenticular lens sheet 120 shown in the first embodiment, thetransmission type screen 400 can provide a finer and superior image.

Modifications of Second Embodiment

(1) The Fresnel lens sheet 410 in this embodiment is a member identicalto the Fresnel lens sheet 110 shown in the first embodiment. Thus, themodifications of the Fresnel lens sheet 110 described in the firstembodiment can be applied to the Fresnel lens sheet 410 in thisembodiment.

(2) In the optical diffusing sheet 420 in this embodiment, glass beadsas a diffusing agent are substantially uniformly mixed in the secondanti-scattering layer 423 and the optical diffusing element basematerial part 422 b, so that they can have diffusing parts,respectively. However, a position of the layer functioning as adiffusing part (where light is diffused without directivity) and thenumber thereof are not specifically limited to this example, and can besuitably changed, similar to the diffusing parts in the lenticular lenssheet 120 in the first embodiment. Although modifications of a diffusingpart are shown below, a constitution of the diffusing part is notlimited to the following modifications.

For example, instead of mixing a diffusing agent in the secondanti-scattering layer 423 in the optical diffusing sheet 420, adiffusing agent may be mixed in the joining layer 424-1 or the joininglayer 424-2. In this case, the optical diffusing element base materialpart 422 b, and the joining layer 424-1 or the joining layer 424-2, inwhich a diffusing agent is mixed, have respectively diffusing parts.Alternatively, instead of mixing a diffusing agent in the opticaldiffusing element base material part 422 b in the optical diffusingsheet 420, a diffusing agent may be mixed in the joining layer 424-1 orthe joining layer 424-2. In this case, the second anti-scattering layer423, and the joining layer 424-1 or the joining layer 424-2, in which adiffusing agent is mixed, have respectively diffusing parts.

Alternatively, an additional diffusing layer formed by substantiallyuniformly mixing a diffusing agent in a polyethylene terephthalate resinmay be laminated on the optical diffusing sheet 420, for example.Instead of mixing a diffusing agent in the second anti-scattering layer423 in the optical diffusing sheet 420, an additional diffusing layermay be laminated, for example, between the second glass substrate 421and the second anti-scattering layer 423, or between the second glasssubstrate 421 and the fourth anti-scattering layer 422. In this example,an all-purpose anti-reflection sheet or the like may be laminated on thesecond anti-scattering layer 423. Alternatively, the secondanti-scattering layer 423 itself may be formed of an anti-glaring sheetor the like.

(3) FIG. 14 is a schematic view of a layer structure of a modificationof the optical diffusing sheet of the second embodiment of thetransmission type screen.

In the optical diffusing sheet 420 in the second embodiment, an exampleis provided to illustrate that the fourth anti-scattering layer 422,that includes the optical diffusing element 422 a and the opticaldiffusing element base material part 422 b. However, the presentinvention is not limited thereto. For example, as shown in FIGS. 14( a)and 14(b), a layer other than the fourth anti-scattering layer 422 inthe transmission type screen 400 may have the optical diffusing elementand the optical diffusing element base material part.

In the example shown in FIG. 14( a), a second anti-scattering layer423-2 has an optical diffusing element 423 a-2 and an optical diffusingelement base material part 423 b-2. According to the optical diffusingsheet 420, light absorbing parts of the optical diffusing element 423a-2 are disposed on a position closest to the emergent side of thetransmission type screen 400. Thus, outside light can be effectivelyabsorbed so as to thereby improve a contrast of an image. In the opticaldiffusing sheet 420 shown in FIG. 14( a), a diffusing agent is mixed inthe optical diffusing element base material part 423 b-2 in a secondanti-scattering layer 423-2, and a fourth anti-scattering layer 422-2,so that they respectively have diffusing parts. However, as describedabove, a position of the layer functioning as a diffusing part wherelight is diffused without directivity and the number thereof are notspecifically limited.

On the other hand, an optical diffusing sheet 420 shown in FIG. 14( b)includes: a second anti-scattering layer 423 containing a diffusingagent mixed therein, that is disposed on a position closest to theemergent side; a fourth anti-scattering layer 422-2 containing adiffusing agent mixed therein, that is disposed on a position closest tothe incident side; a second glass substrate 421 laminated between thesecond anti-scattering layer 423 and the fourth anti-scattering layer422-2; and an optical diffusing element 425 a and an optical diffusingelement base material part 425 b that are laminated between the secondanti-scattering layer 423 and the second glass substrate 421.Disposition of the layer 423 having a diffusing part on the positionclosest to the emergent side can effectively decrease scintillation.Instead of mixing a diffusing agent in the second anti-scattering layer423, an all-purpose diffusing sheet or the like may be laminated on thesecond anti-scattering layer 423.

Third Embodiment

FIG. 15 is a view of a third embodiment of the transmission type screenaccording to the present invention. FIG. 16 is a sectional view of arear projection television using the third embodiment of thetransmission type screen.

As shown in FIG. 15, the transmission type screen 200 in the thirdembodiment includes an optical deflecting sheet 210 disposed on anincident side (light source side) of imaging light L, and an opticaldiffusing sheet 220 disposed on an emergent side (observation surfaceside) of the imaging light L. A combination of the optical deflectingsheet and the optical diffusing sheet is used, as the transmission typescreen, in a rear projection television 2 shown in FIG. 16.

In this transmission type screen, the optical diffusing sheet 220 isformed as the lenticular lens sheet having the lenticular lens used inthe first embodiment. Meanwhile, the optical deflecting sheet 210 isformed as a prism sheet having a prism part (optical deflecting element)formed by arranging a plurality of unit prism portions for deflectinglight.

As shown in FIG. 16, the rear projection television 2 is an imagedisplay device of rear-projection type that includes: the transmissiontype screen 200; a light source part 22 disposed on the incident side ofthe transmission type screen 200, and a mirror part 32 for reflectingimaging light L projected from the light source part 22. The lightsource part 22 is a light source of a single tube type using a DMD, andprojects the imaging light L from below the transmission type screen200. Thus, an incident angle at which the imaging light L is incident onthe transmission type screen 200 is larger than that in the rearprojection television 1.

FIG. 17 is a schematic view of a layer structure of the transmissiontype screen 200 in the third embodiment. A lenticular lens sheet 220 isan optical diffusing sheet that is disposed on the emergent side of thetransmission type screen 200, and includes a second glass substrate 221,a fourth anti-scattering layer 222, a second anti-scattering layer 223,and joining layers 224-1 and 224-2. The lenticular lens sheet 220 is amember identical to the lenticular lens sheet 120 in the firstembodiment. The respective layers correspond to the first glasssubstrate 121, the fourth anti-scattering layer 122, the secondanti-scattering layer 123, and the joining layers 124-1 and 124-2 in thefirst embodiment, and thus have the same functions correspondingthereto. Therefore, the overlapping description for the lenticular lenssheet 220 in the third embodiment is omitted.

Prism Sheet (Optical Deflecting Sheet)

As shown in FIG. 17, a prism sheet 210 includes a first glass substrate211, a first anti-scattering layer 212, a third anti-scattering layer213, and joining layers 214-1 and 214-2, and is disposed on the incidentside of the transmission type screen 200. The first glass substrate 211is a highly rigid substrate having a high light-transmissivity and ahigh rigidity. The first glass substrate 211 in this embodiment is aglass plate with a thickness of 3 mm formed of silicate glass. In thisembodiment, a transmittance of the first glass substrate 211 relative tolight whose wavelength band is between 400 nm and 700 nm is equal to ormore than 90%. The joining layer 214-1 is a layer for integrally joiningthe first glass substrate 211 and the first anti-scattering layer 212which is described below, while the joining layer 214-2 is a layer forintegrally joining the first glass substrate 211 and the thirdanti-scattering layer 213 which is described below. Each of the joininglayer 214-1 and 214-2 may be formed of an acryl resin of pressuresensitive adhesion type which manifests an adhesion property when apressure is applied thereto, and may be 20 m in thickness.

The first anti-scattering layer 212 is integrally laminated on theincident side of the first glass substrate 211 through the joining layer214-1. If the first glass substrate 211 is, for example, broken anddamaged, the first anti-scattering layer 212 exhibits a function forpreventing scattering of pieces of the damaged first glass substrate211. The first anti-scattering layer 212 includes an optical deflectingelement base material part (prism base material part) 212 b, and anoptical deflecting element (prism part) 212 a formed on one surface ofthe prism base material part 212 b. The prism base material part 212 bis a sheet-like member with a thickness of, e.g., 200 μm that serves asa base for the first anti-scattering layer 212. The prism base materialpart 212 b may be formed of an acryl resin, in which glass beads as adiffusing agent are mixed, so as to function as a diffusing part. Thefirst anti-scattering layer 212 as a layered body composed of the prismpart 212 a and the prism base material part 212 b is further laminatedon the first glass substrate 211.

FIG. 18 is a sectional view of the prism part 212 a. As shown in FIG.18, the prism part 212 a includes a plurality of unit prisms 212 e, eachhaving an incident surface 212 c on which the imaging light L isincident, and a total reflection surface 212 d for totally reflecting atleast a part of the light incident from the incident surface 212 c. Asshown in FIG. 15, the unit prisms 212 e are extended along circular arcsof different radii around a point (center point) P at which a normalline from the light source part 22 relative to the prism sheet 210(transmission type screen 200) crosses the prism sheet 210. Theplurality of unit prisms 212 e, which are arranged on the concentricarcs, form the prism part 212 a. Similar to the optical deflectingelement (Fresnel lens part) 113 a in the first embodiment, the prismpart (optical deflecting element) 212 a may be formed by using anultraviolet curing resin.

As shown in FIG. 17, the third anti-scattering layer 213 is integrallylaminated on the emergent side of the first glass substrate 211 throughthe joining layer 214-2. If the first glass substrate 211 is, forexample, broken and damaged, the third anti-scattering layer 213exhibits a function for preventing scattering of pieces of the damagedfirst glass substrate 211. The third anti-scattering layer 213 may beformed by substantially uniformly mixing glass beads as a diffusingagent in a polyethylene terephthalate resin or the like so as tofunction as a diffusing part. A thickness of the third anti-scatteringlayer 213 may be, e.g., 188 μm.

According to the transmission type screen 200 in the third embodimentincluding the lenticular lens sheet (the optical diffusing sheet) 220and the prism sheet 210 of the present invention, effects substantiallythe same as those of the transmission type screen shown in the firstembodiment can be obtained. That is to say, according to thetransmission type screen 200 in the third embodiment, it is possible torestrain the generation of a warp and a float of the optical diffusingsheet 220 or the prism sheet 210, which might be caused by changes inthe environment such as temperature and humidity. It is also possible torestrain the generation of a flexure of the optical diffusing sheet 220or the prism sheet 210, which might be caused by their own weights.Thus, the transmission type screen 200 can have a high degree offlatness, so that an image of high quality can be provided. Similar tothe transmission type screen 100 shown in the first embodiment,according to the transmission type screen 200 in the third embodiment,if the first and second glass substrates 211 and 221 are, for example,broken and damaged, scattering of pieces of the damaged substrates canbe prevented.

The transmission type screen 200 in the third embodiment can furtherprovide the following effects. The optical deflecting sheet 210 in thethird embodiment has, on the incident side of the transmission typescreen 200, the optical deflecting element (prism part) 212 a fordeflecting imaging light incident thereon by totally reflecting thesame. Thus, imaging light projected from the light source part 22 can bedeflected at a large angle so as to emerge as substantially parallellight rays to the observation surface side (emergent side). Thus, asshown in FIG. 16, it is possible to position the light source part 22below the transmission type screen 200, whereby the rear projectiontelevision 2 having a reduced thickness can be attained.

As in the rear projection television 2 in this embodiment, when anincident angle of the imaging light L is large, even a slight warp andfloat of the transmission type screen 200 significantly deteriorates animage quality. In particular, when a float or the like of thetransmission type screen causes a deterioration in image quality, thefurther a point bearing away from the light source part 22 such as anupper side edge of the transmission type screen, the greater the imagequality is affected. However, according to the transmission type screen200 in this embodiment, the prism sheet 210 is formed by integrallylaminating, on the highly rigid first glass substrate 211, all the restlayers constituting the prism sheet 210, and the lenticular lens sheet220 is formed by integrally laminating, on the highly rigid second glasssubstrate 221, all the rest layers constituting the lenticular lenssheet 220. Thus, both the prism sheet 210 and the lenticular lens sheet220 are not easily warped or floated, which might be caused by changesin the environment such as temperature and humidity, and are not easilyinflected because of their own weights. Therefore, it is possible tosignificantly restrain a deterioration in an image of high quality, inthe rear projection television 2 which is vulnerable to a warp, float,and flexure.

Modifications of Third Embodiment

(1) The lenticular lens sheet (the optical diffusing sheet) 220 in thisembodiment is a member identical to the lenticular lens sheet 120 shownin the first embodiment. Thus, the modifications of the lenticular lenssheet 120 described in the first embodiment can be applied to thelenticular lens sheet 220 in this embodiment.

(2) FIG. 19 is a schematic view of a layer structure of a modificationof the prism sheet in the third embodiment of the transmission typescreen.

In the prism sheet 210 in the third embodiment, a diffusing agent suchas glass beads is substantially uniformly mixed in the prism basematerial part 212 b of the first anti-scattering layer 212 and the thirdanti-scattering layer 213, so that they can have diffusing parts,respectively. However, a position of the layer functioning as adiffusing part where light is diffused without directivity and thenumber thereof are not specifically limited to this example, and can besuitably changed.

For example, as shown in FIG. 19, instead of mixing a diffusing agent ina prism base material part 212 b-2 in a prism sheet 210, a diffusingagent may be substantially uniformly mixed in a joining layer 214-1-2,so that the joining layer 214-1-2 can have a diffusing part.Alternatively, although not shown, a diffusing agent may be mixed in ajoining layer 214-2, so that the joining layer 214-2 can have adiffusing agent.

Alternatively, although not shown, instead of mixing a diffusing agentin the prism base material part 212 b and the third anti-scatteringlayer 213 in the prism sheet 210, an additional layer may be laminated,or fine irregular-shaped portions may be formed on a surface of any ofthe layers. In addition, an all-purpose diffusing sheet or the like maybe used as the third anti-scattering layer 213. Alternatively, anoptical sheet, in which a lenticular lens having a weak diffusing effectis formed so as to diffuse light in the vertical or horizontal directionof the transmission type screen 200, may be used as the thirdanti-scattering layer 213.

Fourth Embodiment

FIG. 20 is a view of a fourth embodiment of the transmission type screenaccording to the present invention. As shown in FIG. 20, thetransmission type screen 500 includes an optical deflecting sheet 510disposed on an incident side of imaging light L, and an opticaldiffusing sheet 520 disposed on an emergent side of the imaging light L.Similar to the transmission type screen 200 described in the thirdembodiment, the transmission type screen 500 in the fourth embodiment isused in the rear projection television 2 shown in FIG. 16.

In this transmission type screen, the optical deflecting sheet 510 isformed as a prism sheet having a prism part (an optical deflectingelement), similar to the third embodiment. On the other hand, theoptical diffusing sheet 520 includes an optical diffusing element formedby arranging a plurality of unit optical shape portions each having atotal reflection surface, similar to the second embodiment.

FIG. 21 is a schematic view of a layer structure of the transmissiontype screen in the fourth embodiment. The prism sheet 510 is a memberidentical to the prism sheet 210 described in the third embodiment. Afirst glass substrate 511, a first anti-scattering layer 512, a thirdanti-scattering layer 513, and joining layers 514-1 and 514-2, that areincluded in the prism sheet 510 in this embodiment, respectivelycorrespond to the first glass substrate 211, the first anti-scatteringlayer 212, the third anti-scattering layer 213, and the joining layers214-1 and 214-2, that are included in the prism sheet in the thirdembodiment, and thus have the same functions corresponding thereto.Therefore, the overlapping description for the prism sheet 510 in thefourth embodiment is omitted.

The optical diffusing sheet 520 is a member identical to the opticaldiffusing sheet 420 shown in the second embodiment. A second glasssubstrate 521, a second anti-scattering layer 523, a fourthanti-scattering layer 522 (including unit prism shape portions 440), andjoining layers 524-1 and 524-2, that are included in the opticaldiffusing sheet 520, respectively correspond to the second glasssubstrate 421, the second anti-scattering layer 423, the fourthanti-scattering layer 422, and the joining layers 424-1 and 424-2, thatare included in the optical diffusing sheet 420 in the secondembodiment, and thus have the same functions corresponding thereto.Therefore, the overlapping description for the optical diffusing sheet520 in the fourth embodiment is omitted.

According to the transmission type screen 500 in the fourth embodimentincluding the optical diffusing sheet 520 and the prism sheet (theoptical deflecting sheet) 510 of the present invention, effectssubstantially the same as those of the transmission type screensdescribed in the first to the third embodiments can be obtained.

For example, according to the transmission type screen 500 in the fourthembodiment, it is possible to restrain the generation of a warp and afloat of the optical diffusing sheet 520 or the prism sheet 510, whichmight be caused by changes in the environment such as temperature andhumidity. It is also possible to restrain the generation of a flexure ofthe optical diffusing sheet 520 or the prism sheet 510, which might becaused by their own weights. Thus, the transmission type screen 500 canhave a high degree of flatness, so that an image of high quality can beprovided. Similar to the transmission type screen 100 shown in the firstembodiment, according to the transmission type screen 500 in the fourthembodiment, if the first and second glass substrates 511 and 521 are,for example, broken and damaged, scattering of pieces of the damagedsubstrates can be prevented.

The optical diffusing element 522 a used in the optical diffusing sheet520 can be easily manufactured at a high precision. Thus, the opticaldiffusing sheet, the optical deflecting sheet, and the transmission typescreen that provide a image of high quality can be obtained at lowercosts. In addition, the optical diffusing sheet 520 in the fourthembodiment enables a fine pitch, whereby an image having excellentfineness and quality can be achieved.

The optical deflecting sheet 510 in the fourth embodiment has, on theincident side of the transmission type screen 500, the opticaldeflecting element (prism part) 512 a for deflecting imaging lightincident thereon by totally reflecting the same. Thus, imaging lightprojected from the light source part 22 can be deflected at a largeangle so as to emerge as substantially parallel light rays to theobservation surface side (emergent side). Thus, as shown in FIG. 16, itis possible to position the light source part 22 below the transmissiontype screen 500, whereby the rear projection television 2 having areduced thickness can be attained.

The transmission type screen 500 in the fourth embodiment can furtherprovide the following effects. As in the rear projection television 2shown in FIG. 16, when an incident angle of the imaging light L incidenton the transmission type screen 500 is large, chromatic dispersion ofcolors due to dispersion of refractive index tends to occur at an outerperiphery of the transmission type screen so as to generate chromaticnon-uniformity. However, since the prism sheet 510 and the opticaldiffusing sheet 520 reflect light and emit the same, no chromaticdispersion occurs whereby chromatic non-uniformity can be reduced.

Modification of Fourth Embodiment

The prism sheet (the optical deflective sheet) 510 used in thetransmission type screen 500 in this embodiment is a member identical tothe prism sheet 210 shown in the third embodiment. Thus, themodifications of the prism sheet 210 described in the third embodimentcan be applied to the prism sheet 510 in this embodiment.

The optical diffusing sheet 520 used in the transmission type screen 500in this embodiment is a member identical to the optical diffusing sheet420 shown in the second embodiment. Thus, the modifications of theoptical diffusing sheet 420 described in the second embodiment can beapplied to the optical diffusing sheet 520 in this embodiment.

Fifth Embodiment

FIG. 22 is a view showing a fifth embodiment of the transmission typescreen according to the present invention. FIG. 23 is a schematic viewof a layer structure of the fifth embodiment of the transmission typescreen.

The transmission type screen 300 in the fifth embodiment includes aprism sheet (optical deflecting sheet) including a first anti-scatteringlayer 312 having an optical deflecting element (prism part) 312 a whichis similar to the optical deflecting element (prism part) 212 adescribed in the third embodiment. The transmission type screen 300 inthis embodiment is used in the rear projection television 2 shown inFIG. 16, similar to the transmission type screen 200 shown in the thirdembodiment.

However, the transmission type screen 300 in the fifth embodiment doesnot include a diffusing sheet which is separate from the prism sheet. Inthis embodiment, the prism sheet (optical deflecting sheet) includes, ona position closest to the emergent side, a second anti-scattering layer313 having the optical diffusing element 422 a described in the secondembodiment. The transmission type screen 300 in this embodiment isintegrally constituted only by an optical deflecting sheet (prism sheet)including a first anti-scattering layer 312 having an optical deflectingelement (prism part) 312 a, and the second anti-scattering layer 313having the optical diffusing element 422 a.

As shown in FIG. 23, the transmission type screen 300 in the fifthembodiment is a prism sheet including a glass substrate 311, the firstanti-scattering layer 312, the second anti-scattering layer 313, andjoining layers 314-1 and 314-2. The glass substrate 311 is a highlyrigid substrate layer with a high light-transmissibility and a highrigidity. The glass substrate 311 in this embodiment is a glass plateformed of silicate glass, with a thickness of 3 mm. In this embodiment,a transmittance of the glass substrate 311 relative to light whosewavelength band is between 400 nm and 700 nm is equal to or more than90%. The joining layer 314-1 is a layer for integrally joining the glasssubstrate 311 and the first anti-scattering layer 312, while the joininglayer 314-2 is a layer for integrally joining the glass substrate 311and the second anti-scattering layer 313. Each of the joining layer314-1 and 314-2 may be formed of an acryl resin of pressure sensitiveadhesion type, and may be 20 μm in thickness.

The first anti-scattering layer 312 is integrally laminated on theincident side of the glass substrate 311 through the joining layer314-1. If the glass substrate 311 is, for example, broken and damaged,the first anti-scattering layer 312 exhibits a function for preventingscattering of pieces of the damaged glass substrate 311. The firstanti-scattering layer 312 includes an optical deflecting element basematerial part (prism base material part) 312 b, and an opticaldeflecting element (prism part) 312 a formed on one surface of the prismbase material part 312 b. Similar to the Fresnel lens part 113 adescribed in the first embodiment, the prism part 312 a may be formed byusing an ultraviolet curing resin. The first anti-scattering layer 312as a layered body composed of the prism base material part 312 b and theprism part 312 a is further laminated on the glass substrate 311.

The prism base material part 312 b is a sheet-like member with athickness of, e.g., 200 μm, that serves as a base for the firstanti-scattering layer 312. The prism base material part 312 b may beformed of an acryl resin in which glass beads as a diffusing agent aresubstantially uniformly mixed, so as to function as a diffusing part.The prism part 312 a is formed in the same manner as that of the prismpart 212 b described in the third embodiment, and is formed by arrangingconcentrically a plurality of unit prisms. Each of the unit prisms hasan incident surface on which light is incident, and a total reflectionsurface that totally reflects at least a part of the light incident fromthe incident surface so as to emit the same to the emergent side.

The second anti-scattering layer 313 is laminated on the emergent sideof the glass substrate 311 through the joining layer 314-2. If the glasssubstrate 311 is, for example, broken and damaged, the secondanti-scattering layer 313 exhibits a function for preventing scatteringof pieces of the damaged glass substrate 311.

The second anti-scattering layer 313 includes an optical diffusingelement base material part 313 b, and an optical diffusing element 313 aformed on one surface of the optical diffusing element base materialpart 313 b. Similar to the Fresnel lens part 113 a shown in the firstembodiment, the optical diffusing element 313 a may be formed by usingan ultraviolet curing resin. The second anti-scattering layer 313 as alayered body composed of the optical diffusing element base materialpart 313 b and the optical diffusing element 313 a is further laminatedon the glass substrate 311.

The optical diffusing element base material part 313 b is a sheet-likemember with a thickness of, e.g., 200 μm, that serves as a base for thesecond anti-scattering layer 313. The optical diffusing element basematerial part 313 b may be formed of an acryl resin, in which glassbeads are mixed as a diffusing agent, to function as a diffusing part.

The optical diffusing element 313 a is formed on an emergent-sidesurface of the optical diffusing element base material part 313 b. Theoptical diffusing element 313 a is formed in the same manner as that ofthe optical diffusing element 422 a described in the second embodiment,and is formed by arranging a plurality of unit optical shape portions.Each of the unit optical shape portions has a substantiallytrapezoidal-shaped cross section, and protrudes toward the emergentside.

In addition to the effects shown in the first embodiment, i.e., theimprovement in flatness, and the anti-scattering effect of preventingscattering of pieces when the glass substrate 311 is broken, thetransmission type screen 300 having such a layer structure in the fifthembodiment can provide the following effects. That is to say, thetransmission type screen 300 in the fifth embodiment can be used as aone-piece transmission type screen, without combining a prism sheet andan optical diffusing sheet which are separate from each other. Thus, athickness and a weight of the transmission type screen can be reduced,and a manufacturing cost thereof can be decreased.

In a transmission type screen including, in combination, a prism sheetand an optical diffusing sheet which are separate from each other, evenwhen only one of the sheets is warped, a float (clearance) isundesirably generated between the sheets. Thus, there is a problem inthat an image deterioration such as blurring of image is likely tooccur. However, in the integrally-formed transmission type screen 300 inthis embodiment, a unitary sheet-like member constitutes thetransmission type screen, and the transmission type screen has a highdegree of flatness. Thus, deterioration in image quality, which might becaused by a float or the like, can be prevented.

In addition, on the incident side of the transmission type screen 300 inthe fifth embodiment, there is disposed the optical deflecting element(prism part) 312 a that totally reflects and deflects imaging lightincident thereon. Thus, imaging light projected from the light sourcepart 22 can be deflected at a large angle so as to emerge assubstantially parallel light rays to the observation surface side(emergent side). Thus, as shown in FIG. 16, it is possible to positionthe light source part 22 below the transmission type screen 200, wherebythe rear projection television 2 having a reduced thickness can beattained.

Modifications of Fifth Embodiment

(1) In this embodiment, an example is provided to illustrate that thesecond anti-scattering layer 313 includes the optical diffusing element313 a formed by arranging a plurality of unit optical shape portionseach having a substantially trapezoidal-shaped cross-section. However,not limited thereto, instead of the optical diffusing element 313 a, alenticular lens may be disposed that is formed by arranging a pluralityof unit lenses each having a substantially semielliptic-shapedcross-section. Alternatively, the second anti-scattering layer 313 mayhave a highly omnidirectional diffusing effect, or an all-purposediffusing sheet may be used as the second anti-scattering layer 313.

(2) FIGS. 24 and 25 are schematic views respectively showing layerstructures of modifications of the fifth embodiment of the transmissiontype screen.

In the above-described transmission type screen 300 in the fifthembodiment, glass beads as a diffusing agent are mixed in the prism basematerial part 312 b and the optical diffusing element base material part313 b, so that the prism base material part 312 b and the opticaldiffusing element base material part 313 b can function as diffusingparts. However, not limited to this example, a position of the layerfunctioning as a diffusing part and the number thereof in the sheet-likemember are not specifically limited, which is similar to theabove-described first to fourth embodiments. Although modifications ofthe diffusing part are shown below, a constitution of the diffusing partis not limited to the following modifications.

In the example shown in FIG. 24( a), an additional diffusing layer 315-1serving as a second anti-scattering layer is laminated on a positionclosest to the emergent side of the transmission type screen 300 (prismsheet) through a joining layer 314-3. The diffusing layer 315-1 may beformed by mixing a diffusing agent such as glass beads in a polyethyleneterephthalate resin or the like. A thickness of the diffusing layer315-1 may be, for example, 188 μm. Alternatively, an all-purposediffusing sheet may be used as the diffusing layer 315-1. The provisionof the additional diffusing layer can improve a diffusion uniformity. Inparticular, imaging light diffused by an optical diffusing element 313 ahas a tendency of forming three peaks, that is to say, imaging lightthat is totally reflected by the optical diffusing element 313 a in onedirection, imaging light that is totally reflected by the opticaldiffusing element 313 a in the other direction, and imaging light thatis not totally reflected by the optical diffusing element 313 a so as topass through the optical diffusing element 313 a. However, in thetransmission type screen in this modification having the diffusing layerdisposed on the emergent side from the optical diffusing element 313 a,the imaging light is randomly diffused, whereby the transmission typescreen 300 (prism sheet) can have a moderate luminance distribution.However, a lamination position of the additional diffusing layer is notspecifically limited. For example, as shown in FIG. 24( b), thediffusing layer may be laminated between the glass substrate 311 and thefirst anti-scattering layer 312 through joining layers 313-4 and 314-5.

In the examples shown in FIGS. 25( a) to 25(c), an optical diffusinglayer 316 including an optical diffusing element 316 a and an opticaldiffusing element base material part 316 b, which respectively have thesame constitutions as those of the optical diffusing element 313 a andthe optical diffusing element base material part 313 b in theabove-described fifth embodiment, is integrally joined between the firstanti-scattering layer 313 and the glass substrate 311. That is to say,in the example shown in FIGS. 25( a) to 25(c), both the opticaldiffusing element 316 a and the optical deflecting element (prism part)312 a are disposed on positions closer to the incident side than theglass substrate 311.

Specifically, in the transmission type screen shown in FIG. 25( a), anoptical diffusing layer 316 for diffusing light is laminated between thefirst anti-scattering layer 312 and the glass substrate 311 throughjoining layers 314-6 and 314-7. In this example, a secondanti-scattering layer 313-2 may be made to be a diffusing part (secondanti-scattering layer 313-2-2) by mixing therein a diffusing agent. Inthis transmission type screen 300, an anti-reflection sheet having afunction of preventing reflection, and an anti-glaring sheet having afunction of preventing glaring may be laminated on the secondanti-scattering layer 313-2 that is integrally laminated on the emergentside of the glass substrate 311 through a joining layer 314-8.Alternatively, in this transmission type screen 300, instead of mixing adiffusing agent in the second anti-scattering layer 312-2, a diffusingagent may be substantially uniformly mixed in the joining layer 314-8,for example, so that the joining layer 314-8 can have a diffusing part.

As shown in FIG. 25( d), an additional diffusing layer 315-3 may befurther laminated on the transmission type screen 300 in FIG. 25( c). Inthe example shown in FIG. 25( d), the diffusing layer 315-3 is laminatedbetween an optical diffusing layer 316 and a glass substrate 311 throughjoining layers 314-9 and 314-10. Alternatively, as illustrated, insteadof mixing a diffusing agent in the second anti-scattering layer, adiffusing agent may be mixed in the joining layer 314-8-2 between theglass substrate 311 and the second anti-scattering layer 313-2, so thatthe joining layer 314-8-2 can have a diffusing part. In this example, ananti-reflection sheet having a function of preventing reflection, and ananti-glaring sheet having a function of preventing glaring may belaminated on the second anti-scattering layer 313-2.

Alternatively, as shown in FIG. 25( e), two or more additional diffusinglayers 315-3 and 315-4 may be further laminated on the transmission typescreen 300 in FIG. 25( c). The constitution of the transmission typescreen shown in FIG. 25( e) on the incident side from a glass substrateis identical to that of the transmission type screen shown in FIG. 25(d). On the other hand, in the example shown in FIG. 25( e), a furtheradditional diffusing layer 315-4 is laminated between the glasssubstrate 311 and a second anti-scattering layer 313-2 through joininglayers 314-11 and 314-12. In the example shown in FIG. 25( e), anall-purpose anti-reflection sheet and an anti-glaring sheet may belaminated on the second anti-scattering layer 313-2.

Modifications Common to the First to Fifth Embodiments

Not limited to the above-described embodiments, various changes andalterations are possible.

(1) In the above-described first to fifth embodiments, an example isprovided to illustrate that the transmission type screen includes onlyone layer having an optical diffusing element, which layer is alsoreferred to as “optical diffusing layer”. However, not limited thereto,the transmission type screen may have two or more optical diffusinglayers. Such examples are described with reference to the drawings.

FIG. 26 is a perspective view of assistance in explaining a layerstructure of the transmission type screen including two or more opticaldiffusing elements. FIG. 27 is a schematic view of a layer structure ofthe transmission type screen shown in FIG. 26.

The transmission type screen 500 shown in FIGS. 26 and 27 is amodification of the transmission type screen 500 described referring toFIG. 21. In addition to the structure shown in FIG. 21, the transmissiontype screen 500 shown in FIGS. 26 and 27 further includes a secondoptical diffusing layer 527 having a second optical diffusing element527 a. The optical diffusing layer 527 is integrally joined between asecond glass substrate 521 and a fourth anti-scattering layer 522through joining layers 524-6 and 524-7.

As shown in FIG. 26, a first optical diffusing element 522 a included inthe fourth anti-scattering layer 522 is formed by arranging, in ahorizontal direction, for example, a plurality of unit optical shapeportions 522 c each having a substantially trapezoidal-shapedcross-section. Thus, imaging light passing through the fourthanti-scattering layer (first optical diffusing layer) 522 is diffused inthe horizontal direction. In the first optical diffusing element 522 a,light absorbing parts 522 d are buried between the respective unitoptical shape portions 522 c. Thus, as shown in FIG. 26, the lightabsorbing parts 522 d are arranged in the horizontal directioncorresponding to the unit optical shape portions 522 c.

On the other hand, as shown in FIG. 26, the second optical element 527 aincluded in the second optical diffusing element 527 is formed byarranging, in a vertical direction, for example, a plurality of unitoptical shape portions 527 c each having a substantiallytrapezoidal-shaped cross-section. Thus, imaging light passing throughthe second optical diffusing layer 527 is diffused in the verticaldirection. In the second optical diffusing element 527 a, lightabsorbing parts 527 d are buried between the respective unit opticalshape portions 527 c. Thus, as shown in FIG. 26, the light absorbingparts 527 d are arranged in the vertical direction corresponding to theunit optical shape portions 527 c.

According to the transmission type screen 500, imaging light can bediffused by the two optical diffusing elements in two directions,preferably, in two directions perpendicular to each other, and morepreferably in the vertical and horizontal directions. Then, patternsprojected on the transmission type screen 500 can be observed from awide viewing angle. The light absorbing parts arranged in twodirections, preferably, two directions perpendicular to each other, caneffectively absorb light other than imaging light, such as outside lightor stray light, whereby a contrast can be significantly improved.

The transmission type screen other than the fourth embodiment can bemodified so as to include a plurality of optical diffusing layers. Forexample, the example shown in FIG. 28 is a modification of thetransmission type screen in the first embodiment shown in FIG. 3.Besides, for example, the example shown in FIG. 29 is a modification ofthe transmission type screen in the fifth embodiment shown in FIG. 25(c). Both of the transmission type screens can enlarge a viewing angleand significantly enhance a contrast.

In these modifications, not limited to the illustrated ones, positionsof the first diffusing layer and the second diffusing layer can besuitably changed. In addition to the optical diffusing element formed byarranging a plurality of unit optical shape portions each having asubstantially trapezoidal-shaped cross-section described by using FIG.13, the optical diffusing element to be used may be an optical diffusingelement formed of a lenticular lens.

(2) FIGS. 30 to 32 are schematic views of layer structures ofmodifications of the transmission type screen according to the presentinvention.

In the above-described first to fourth embodiments, although an exampleis provided to illustrate that each of the optical defecting sheet andthe optical diffusing sheet used in the transmission type screen has thehighly rigid substrate, the present invention is not limited thereto.

For example, as shown in FIG. 30, a Fresnel lens sheet 130 including aplastic substrate 131 formed of a plastic resin on which surface aFresnel lens part 132 of substantially the same shape as that of theFresnel lens part 113 a that is formed by an ultraviolet curing resinmay be used in combination with an optical diffusing sheet including ahighly rigid substrate layer. The example shown in FIG. 30 is amodification of the transmission type screen in the first embodimentshown in FIG. 3. The plastic substrate 131 may be formed of an acrylresin, polystyrene resin, methyl methacrylate styrene copolymer resin(MS resin), methyl methacrylate butadiene styrene copolymer resin (MBSresin), and so on, and may be a plate-like member with a thickness of,e.g., 2 mm. As shown in FIG. 30, the plastic substrate 131 may functionas a diffusing part by mixing therein a diffusing agent such as glassbeads. Since it is technically easy to mix a diffusing agent in theplastic substrate 131, a manufacturing cost for such a transmission typescreen can be decreased.

Since the Fresnel lens sheet 130 uses the plastic substrate 131, aweight of the transmission type screen can be reduced. However, a warpand a float of the Fresnel lens sheet 130 are likely to occur by changesin the environment. Thus, in order to restrain a warp and a float causedby changes in the environment, the transmission type screen ispreferably constituted by the Fresnel lens sheet 130 with a curvature,such that the Fresnel lens sheet 130 is convex toward the lenticularlens sheet 120. By this constitution, a flatness of the Fresnel lenssheet 130 can be maintained.

Similarly, instead of a highly rigid substrate made of glass, theFresnel lens sheet 410 shown in the second embodiment, the prism sheet210 shown in the third embodiment, and the prism sheet 510 shown in thefourth embodiment may also use a substrate made of plastics.

In the first to fourth embodiments, the transmission type screen may usea substrate made of plastics in the optical diffusing sheet, instead ofthe highly rigid substrate made of glass. The example shown in FIG. 31is such a modification of the transmission type screen in the firstembodiment shown in FIG. 3. The example shown in FIG. 32 is such amodification of the transmission type screen in the third embodimentshown in FIG. 17. In the examples shown in FIGS. 31 and 32, lenticularlens parts 142 and 242 are respectively formed on incident-side surfacesof lenticular lens base material parts 141 and 241. Plastic substrates143 and 243 are respectively formed on emergent-side surfaces of thelenticular lens base material parts 141 and 241 through joining layers144 and 244.

In the examples shown in FIGS. 31 and 32, the lenticular lens basematerial parts 141 and 241 may be constituted in the same manner as thatof the above-described plastic substrate 131 shown in FIG. 30. Thejoining layers 144 and 244 may be formed of an acryl resin ofultraviolet curing type, and may be 100 μm in thickness. The plasticsubstrates 143 and 243 may be formed by mixing a diffusing agent such asglass beads in a polystyrene resin, methyl methacrylate styrenecopolymer resin (MS resin), methyl methacrylate butadiene styrenecopolymer resin (MBS resin), and so on. Although it is preferable thatthe plastic substrates 143 and 243 have a thickness of 2 mm to 3 mm, thethickness is not specifically limited. In FIGS. 31 and 32, the plasticsubstrates 143 and 243 are illustrated to have a single layer structure.However, not limited thereto, the plastic substrates 143 and 243 may beof a two-layered structure including a diffusing layer containingtherein a diffusing agent such as glass beads, and a layer withoutdiffusing agent, or may be a multi-layered structure including ananti-reflection sheet having a function of preventing reflection.

(3) In the respective embodiments, in order to impart a diffusingfunction for diffusing light without directivity, glass beads as adiffusing agent is substantially uniformly mixed in the Fresnel basematerial parts 113 b and 413 b; the prism base material parts 212 b, 312b, and 512 b; the lenticular base material parts 122 b and 222 b, theoptical diffusing element base material parts 313 b, 422 b, and 522 b,the second anti-scattering layers 123, 223, 423, and 523; and the thirdanti-scattering layers 213 and 513. However, as has been describedabove, a method of imparting a diffusing function is not limited tothese example. For example, a diffusing agent may be substantiallyuniformly mixed in the joining layers 114-1, 114-2, 124-1, 124-2, 214-1,214-2, 224-1, 224-2, 314-1, 314-2, 414-1, 414-2, 424-1, 424-2, 514-1,514-2, 524-1, and 524-2, so that a diffusing function is imparted tothese joining layers.

Alternatively, it is possible to impart a diffusing function by formingfine irregular-shaped portions on a surface of any of the layers. Inthis case, a difference between refractive indexes of the adjacent twolayers, between which a surface having the fine irregular-shapedportions is placed, is preferably large, which produces an excellentdiffusing effect.

A diffusing agent is not specifically limited, and may be particlesformed of an organic compound such as plastics. However, it ispreferable that the diffusing agent have dimensions that are notdependent on a wavelength of light.

(4) In the transmission type screens 100, 200, 300, 400, and 500 of therespective embodiments, it is preferable that two or more layers whichare not adjacent to each other have diffusing parts having a diffusingeffect. In this case, it is possible not only to enlarge a viewingangle, but also to effectively reduce scintillation (glaring on thescreen). When the number of layers having a diffusing part is two ormore, a total amount of a diffusing agent to be mixed can be decreased.

As has been described above, a position of the layer functioning as adiffusing part is not specifically limited. However, it is not preferredthat a diffusing agent is mixed in the first and second glass substrates111, 121, 211, 221, 311, 411, 421, 511, and 521, since mixing of thediffusing agent therein makes the substrates fragile and easily to bebroken.

(5) In the respective embodiments, the light source parts 21 and 22 arelight sources of a single tube type using a DMD. However, not limitedthereto, the light source parts 21 and 22 may be light sources of asingle tube type using an LCD, for example. Alternatively, the lightsource part 21 in the first embodiment may be a light source of a tripletube type using a CRT.

(6) In the respective embodiments, the Fresnel base material parts 113 band 413 b; the prism parts 212 b, 312 b, and 512 b; the lenticular basematerial parts 122 b and 222 b; the optical diffusing element basematerial parts 313 b, 422 b, and 522 b are formed of an acryl resin.However, not limited thereto, a material thereof is not specificallylimited, and may be a polyester resin, polyethylene resin, polycarbonateresin, and so on, for example.

When the light source parts 21 and 22 are light sources having apolarization dependency, such as an LCD, it is possible to use, as thesebase material parts, a sheet-like member formed of cellulose basedresins such as triacetyl cellulose, or a member with a low doublerefraction such as a non-stretched polycarbonate plate or the like, soas to reduce stray light and improve an image quality.

(7) In the respective embodiments, the Fresnel lens parts 113 a and 413a formed of an ultraviolet curing resin are integrally formed on theFresnel base material parts 113 b and 413 b, respectively. The opticaldiffusing elements 313 a, 422 a, and 522 a formed of an ultravioletcuring resin are integrally formed on the optical diffusing element basematerial parts 313 b, 422 b, and 522 b, respectively. The prism parts212 a, 312 a, and 512 a formed of an ultraviolet curing resin areintegrally formed on the prism base material parts 212 b, 312 b, and 512b, respectively. The lenticular lens parts 122 a and 222 a formed of athermoplastic resin are integrally formed on the lenticular basematerial parts 122 b and 222 b, respectively. However, materials formingthe Fresnel lens parts, optical diffusing elements, prism parts, andlenticular lens parts are not limited to an ultraviolet curing resin anda thermoplastic resin, and can be suitably changed. For example, a heatcuring resin may be used. A forming method of these parts is notspecifically limited, and various methods such as extrusion molding orthe like may be used.

(8) In the first to fourth embodiments, glass beads as a diffusing agentare mixed in the second anti-scattering layers 123, 223, 423, and 523,so that these layers can function as diffusing parts. However, notlimited thereto, these layers may have at least one of the followingfunctions: anti-reflection function, anti-glaring function, coloringfunction, dimmer function (light fading function), ultravioletabsorption function, antistatic function, soil-resistant function,sensing function, or hard-coating function. In this case, the followingeffects can be expected.

The second anti-scattering layers 123 and 223 are laminated on aposition closest to the emergent side (closest to the observationsurface side). Thus, when the second anti-scattering layers have ananti-reflection function, spoil by outside light can be effectivelyprevented. When the second anti-scattering layers have an ultravioletabsorption function, it is possible to prevent the lenticular basematerial parts 123 b and 222 b from turning yellow, which might becaused by ultraviolet light contained in outside light. When the secondanti-scattering layers have an anti-glaring function, glaring on thescreen can be restrained. When the second anti-scattering layers have ahard-coating function, a hardness of an exposed surface of the screencan be elevated, whereby the screen can be restrained from beingscratched. When the second anti-scattering layers, have an antistaticfunction, a static electricity generated on the transmission type screencan be removed, so that an attachment of dirt or the like on the screencan be prevented. When the second anti-scattering layers have asoil-resistant function, a surface of the screen can be prevented frombeing soiled. When the second anti-scattering layers have a coloringfunction and an dimmer function, a contrast can be enhanced to improvean image quality. When the second anti-scattering layers have a sensingfunction, the screen can be used in a touch sensor or the like.

Alternatively, an all-purpose sheet having at lest one of the followingfunctions: diffusing function, anti-reflection function, anti-glaringfunction, coloring function (Tint), dimmer function (ND), ultravioletabsorption function, antistatic function, soil-resistant function,sensing function, or hard-coating function, may be used as the secondanti-scattering layers 123, 223, 423, and 523. Alternatively, asheet-like member formed of an acryl resin or the like may be subjectedto a treatment so as to have at least one of these functions. Methods ofimparting these functions are not specifically limited. For example, aplurality of sheets having the respective functions may be laminated, ora sheet may be subjected to a treatment so as to have a plurality offunctions. Not limited to the second anti-scattering layers 123, 223,423, and 523, other anti-scattering layers can suitably have thesefunctions.

(9) In the first to fifth embodiments, the first glass substrates 111,211, 411, and 511, and the second glass substrates 121, 221, 421, and521, and the glass substrate 311 are glass plates made of silicate glasswith a thickness of 2 mm or 3 mm. However, the constitution of the glasssubstrates is not limited thereto. As far as a material has alight-transmissibility and a high rigidity, no-alkali glass, phosphateglass, borate glass, soda-lime glass, kali glass, quartz glass, leadglass, barium glass, borosilicate glass, or phosphoric-base glass may beused as a material for a glass plate (highly rigid substrate).Alternatively, an air-blast cooling tempered glass and a chemicallytempered glass may be used as a glass plate (highly rigid substrate).Besides, a plate-like member formed of light-transmissible ceramics witha light-transmissibility may be used as a glass plate (highly rigidsubstrate). A thickness of a member used as the substrate is preferablyin a range between 1.5 mm to 3 mm, but is not limited thereto.

(10) In the first embodiment, the joining layers 114-1, 114-2, 124-1,and 124-2 are layers for integrally joining the first glass substrate111 and the first anti-scattering layer 112, the first glass substrate111 and the third anti-scattering layer 113, the second glass substrate121 and the second anti-scattering layer 123, and the second glasssubstrate and the fourth anti-scattering layer 122. However, a diffusingagent such as glass beads may be substantially uniformly mixed in thesejoining layers, so that the joining layers can also function asdiffusing parts. Alternatively, an ultraviolet absorbing agent may bemixed in the joining layer 124-2 positioned near a position closest tothe emergent-side surface of the transmission type screen 100. In thiscase, the screen can be restrained from turning yellow, which might becaused by ultraviolet light contained in outside light. The samemodification can be applied to the joining layers 214-1, 214-2, 224-1,224-2, 314-1, 314-2, 414-1, 414-2, 424-1, 424-2, 514-1, 514-2, 524-1,and 524-2 in the second to fifth embodiments.

In the first to third embodiments, the joining layers 114-1, 114-2,124-1, 124-2, 224-1, 224-2, 414-1, and 414-2 are formed of an acrylresin of ultraviolet curing type that cures by an ultravioletirradiation. In the second to fifth embodiments, the joining layers214-1, 214-2, 314-1, 314-2, 424-1, 424-2, 514-1, 514-2, 524-1, and 524-2are formed of an acryl resin of pressure sensitive adhesion type whichmanifests an adhesion property when a pressure is applied thereto.However, materials used for these joining layers are not limited tothese examples, and an acryl ester resin, phenol-base resins may beselected as a material for use in the joining layers. The joining manneris not specifically limited, and resins of heat curing type, ultravioletcuring type (UV curing type), electron radiation curing type (EB curingtype), pressure sensitive adhesion type (PSA) or the like can beselected as a material for the joining layers. A thickness of thejoining layer is preferably in a range of from 5 μm to 200 μm, but isnot limited thereto.

(12) In the first to fifth embodiments, glass beads are used as adiffusing agent to be mixed in the respective layers. However, notlimited thereto, a publicly-known diffusing agent including acryl-baseddiffusing agents and styrene-based diffusing agents may be usedtherefor. In the first to fifth embodiments, glass beads as a diffusingagent is substantially uniformly mixed in a polyethylene terephthalateresin or the like, in order to dispose an additional diffusing layer.However, not limited thereto, other publicly-known diffusing layers maybe used, that are formed by, for example, mixing glass beads as adiffusing agent in PET, coating PET with various diffusing agents, ormixing various diffusing agent substantially uniformly in apolycarbonate resin.

What is claimed:
 1. An optical deflecting sheet for use in atransmission type screen that emits imaging light projected from anincident side to an emergent side, comprising: a highly rigid substratelayer with a light-transmissibility and a high rigidity; and two or morelayers laminated on the highly rigid substrate layer, the layersincluding at least a pair of anti-scattering layers disposed on oppositesides of the highly rigid substrate layer for preventing scattering ofthe highly rigid substrate layer; wherein at least one layer of the twoor more layers includes an optical deflecting element that deflectsimaging light by refracting or reflecting the imaging light; wherein theoptical deflecting element is a prism part formed by arranging aplurality of unit prisms each having an incident surface on which lightis incident and a total reflecting surface for reflecting at least apart of light incident on the incident surface; wherein at least onelayer of the two or more layers has a diffusing part that diffuseslight, and wherein the highly rigid substrate layer is formed of glassor translucent ceramic.
 2. The optical deflecting sheet according toclaim 1, wherein at least one layer of the two or more layers that islaminated on a position closer to the incident side than the highlyrigid substrate layer, and at least one layer of the two or more layersthat is laminated on a position closer to the emergent side than thehighly rigid substrate layer, have the diffusing parts, respectively. 3.The optical deflecting sheet according to claim 1, wherein the two ormore layers includes a joining layer that is interposed between thehighly rigid substrate layer and the anti-scattering layer so as to jointhe highly rigid substrate layer and the anti-scattering layer to eachother; and the joining layer includes at least one of a diffusing agentfor diffusing light and an ultraviolet absorbing agent for absorbingultraviolet light.
 4. A transmission type screen comprising the opticaldeflecting screen according to claim 1.